Refining of oil



Feb. 10, 1942. R. o. lBl-:NDR 2,272,596

REFINING OF OIL Filed Dec. 9, 1940` 2 sheets-sheet 1 Jef/Ier BY- IATTORNEY Feb. 1o, 1942, R o, BNDER 2,272,596.

REFINING oF on.

ATTORNEYS Patented Feb. 10, 1942 UNITE STATS trieste ortica REFININ G OFOIL Richard 0. Bender, Ridley Park, Pa., assignor to Sinclair RefiningCompany, New York, N. Y., a corporation of Maine Application December 9,1940, Serial No. 369,218

(Cl. 19E-29) Claims.

This invention relates to the rening of petroleum oils, and, moreparticularly, of light petroleum distillates such as kerosene andgasoline. 'Ihe invention provides a novel process for removingundesirable sulphur compounds from such distillates which is especiallyuseful in the treatment of very sour distillates such as polymergasoline. This application is in part a continuation of my copendingapplication Serial No. 300,439 led October 20, 1939.

Light petroleum distillates contain undesirable sulphur compounds, such,for example, as mercaptans which impart to the distillates anobjectionable odor and corrosiveness. These distillates, known as sourdistillates, have been the object of a multitude of processes devisedfor the purpose of removing undesirable sulphur compounds from suchdistillates, an operation known as sweeteningJ Treatment of sourdistillates with sodium plumbite, the so-called doctor treatment, hasbeen generally adopted in the art as the most efcient method ofsweetening such distillates. The doctor treatment, however, requires theuse of large volumes of aqueous treating solutions with attendant highlosses of distillates and of expensive treating solutions, due to theformation of emulsions and to incomplete Washing of treating solutionsfrom treated distillates. Moreover, the handling of large volumes ofsuch aqueous solutions requires a large labor force and further presentsa serious problem during cold Weather, and this problem has beencharacteristic of other sweetening operations employing large volumes ofaqueous solutions.

More recently there have been attempts to sweeten sour distillates byprocesses which propose to avoid handling of substantial amounts ofaqueous solutions, these processes being known as dry sweetening. Leadsulphide has been used heretofore as a catalyst in such dry sweeteningprocesses utilizing elemental sulphur and free oxygen to remove theundesirable sulphur compounds from the distillates, but the methodshereinbefore attempted have been less ecient than the conventionaldoctor treatment and have been further characterized, as in theconventional doctor treatment, by a loss of anti-knock Value, indicatedfor example by a decrease of at least 1/2 point in the octane number, ingasoline so treated.

I have found that undesirable sulphur compounds contained in a lightpetroleum distillate may be removed effectively and economically byincorporating in such a distillate elemental sullates such as gasoline.

phur and an amount of an alkaline compoundl suiicient to render thedistillate alkaline, and by then subjecting the alkaline distillatecontaining elemental sulphur to the action of a lead sulphide catalyst.This process is as eliective as the conventional doctor sweeteningWithout the disadvantages inherent in doctor sweetening and it does notreduce the anti-knock value of distil- I have found that in thetreatment of very sour distillates it is desirable to introduce into the.distillate prior to contact with the lead sulphide catalyst an alkalihydroxide in a quantity in excess of of that theoretically required tomaintain the distillate alkaline and also a limited amount of finelydispersed water, preferably introduced in the formv of steam, as aWashing agent. I have also found it to be desirable to contact thealkaline distillate with the lead sulphide catalyst in a plurality ofsuccessive stages, the majority of the mercaptans being converted in thefirst stage and the remaining more refractory mercaptans in a succeedingstage or stages.

I have discovered that contact between the'distillate and the leadsulphide catalyst can be efiected in the absence offree oxygen. Thusdeliberate introduction of air, or the like, into the alkalinedistillate charged to the -catalyst bed is' not required. The presenceof adventitious air does not appreciably affect normal operation of myprocess.

to oxidize the lead sulphide catalyst thus requiring the use of excesssulphur in the untreated distillate to maintain the catalyst in thedesired form of lead sulphide.

In carrying out my process the amount ci elesirable in the treatment ofgasoline because it ef-` fects a reduction in the anti-knock value ofthe gasoline under treatment.

In as much as the mercaptans comprise the most important sulphurcompounds to be eliminated from light distillates such as gasoline, themercaptan content of such distillate serves as an index of the amount ofsulphur required in my However, the presence of any ap-v` preciablequantity of air in the distillater tends verse eiect in the sweeteningoperation and the undesirability of its presence in the nished gasoline.The prolonged use of excess sulphur materially shortens the life of thelead sulphide catalyst. However, I have found that the sensitivity ofthe catalyst to variations in the sul phur content and alkalinity of thesour distillate diminishes with an increase in the size of the catalystvessel used.

I have found that lead sulphide deposited on saw-dust is an excellentcatalyst which may be used with particular advantage although goodresults may also be obtained with a catalyst comprising lead sulphidedeposited on carborundum or other carrier which suiliciently resistspacking. A saw-dust carrier which I have found to be particularlyadvantageous comprises saw-dust classied to pass through a l mesh screenbut suilciently coarse not to pass through a mesh screen. This carrierprovides a large surface with attendant high catalytic efficiency.Furthermore the saw-dust carrier reduces the tendency to pack into acomparatively impervious bed. 'Ihe lead sulphide may be deposited on thesawdust carrier by admixing saw-dust wet with gasoline, with litharge(PbO) in such proportion that the litharge comprises about 35%-70%, or,as now preferred, about 40%-50% by weight of the mixture, then passingthrough a bed of this mixture in a suitable tower a charge of alkalinegasoline containing a substantial excess of elemental sulphur until thelitharge is largely con- Verted to lead sulphide as evidenced by theprogressively increased sweetening of gasoline discharged from the bed.The catalyst thus .produced, comprising lead sulphide deposited onsaw-dust and containing about %-'70% lead sulphide by weight, or about40%-50% lead sulphide when starting with a mixture containing 40%-50%lead oxide, may then be used in the normal sweetening operation in whichthe use of excess sulphur in the gasoline charge is avoided. I havefound, however, that the catalyst thus prepared usually does not remainactive for a very long period but that after initial reactivation it isin condition to be used over long periods of activity between successivereactivations. Reactivation of spent catalyst may be eiected b-ysteaming the bed of catalyst for several hours, then washing thecatalyst with water until substantially free from water solublematerials, removing and drying the catalyst, and subsequently replacingthe catalyst in the catalyst tower. creased reactivation of the catalystmay in some instances be provided by washing the replaced catalyst withacetone and displacing the acetone with gasoline so as to moisten thebody of catalyst with gasoline. Although washing of the catalyst withacetone is not vital to successful operation of my sweetening process,it may increase, by 20 %25% in certain instances, the active period ofthe catalyst between successive reactivations. I have found that wettingof the saw-dust, in admixture with litharge or with lead sulphide (inthe case of reactivated catalyst) with gasoline reduces packing of thesaw-dust carrier during subsequent normal operation. To insure wettingof the dry catalyst with gasoline it is desirable first to fill thecatalyst chamber with gaso line and then to introduce the dried catalystthus insuring thorough wetting.

The alkalinity of the distillate subjected to the action of the catalystshould be controlled so that a slight excess is always available. Byexcess alkalinity I mean that the sweetened distillate after treatmentwith the catalyst should be slightly alkaline, thus assuring thepresence of a sufficient amount of alkaline compound after the catalysttreatment. For example, about 6-7 pounds of NaOH per thousand barrels ofgasoline is usually satisfactory in the treatment of a heavystraight-run gasoline. About 12 pounds of NaOH per thousand barrels isordinarily required for the treatment of depropanized straight-rungasoline flashed from crude oil at 340 F. and 40 pounds pressure.Similarly I have found that about 20 pounds of NaOH per thousand barrelsmay be used with advantage for the treatment of reformed straight-rungasoline while the amount of alkaline compound should be still furtherincreased when treating very sour polymer gasolines. Alkalinity may beimparted to the gasoline by ammonia in the gaseous state or in the formof aqua ammonia, ammonia having the advantage of providing greatflexibility in the control of the alkalinity of the distillate.

The desired alkalinity may be imparted to the distillate wholly or inpart by a preliminary lye washing operation in accordance withconventional renery practice. Excessive alkalinity reduces the activityof the catalyst by rendering it readily susceptible to wetting bymoisture entrained in the gasoline and excessive wetting of the catalystadversely aiects the action of the catalyst. When several successivecatalyst Zones are employed in my process excessive alkalinity may beavoided by imparting limited alkalinity to the distillate in advance ofeach successive stage thus minimizing the proportion of alkalinecompound present at the initial catalyst contact. Decient alkalinitycauses the catalyst to become poisoned thus requiring more frequentreactivation of the catalyst. However, I have found that a lead sulphidecatalyst poisoned in this manner may be reactivated by pouring aqueousammonia over the catalyst and then allowing it to stand for severalhours before reuse.

The presence of excessive quantities of entrained moisture should beavoided in the alkaline distillate charged to the catalyst bed. The mostadvantageous amount of entrained moisture in a distillate to be treatedby my sweetening process depends largely upon the character of thedistillate and its treatment prior to sweetening by my process. Theamount of moisture ordinarily entrained in sour gasoline is notdetrimental. When treating a relatively sweet straight-run gasoline theamount of moisture should be kept at a minimum as moisture wets thecatalyst bed causing it to pack and thus to impede the flow of gasolinethrough the catalyst bed. When treating such relatively sweet gasolinesthe rate of flow through the catalyst bed is advantageously maintainedat a high rate. Therefore any considerable tendency of the catalyst bedto pack causes the pressure drop through the catalyst bed to becomeobjectionably high in a period 0f time much shorter than that requiredto accumulate an objectionable deposit of sodium and ammonium salts inthe catalyst bed. Initial treatment of a distillate with an aqueouscaustic solution or aqueous ammonia may introduce into the distillate anexcessive amount of water which should not be carried over into thecatalyst bed particularly when treating relatively sweet distillates andfor this reason adequate means should be provided for separation of suchwater from the alkaline distillate before it is charged to the catalystwhen treating a distillate of this type.

On the other hand when treating very sour distillates, as for examplepolymer gasoline, a low rate of flow through the catalyst bed isrequired. Accordingly, the pressure drop due to packing of the catalystbed is a less serious factor. In addition when treating such very sourstocks, water soluble salts, such as the salts produced byneutralization of HzS with NaOH, with ammonia, or with a mixture of NaOHand ammonia, accumulate in the catalyst bed at a rate suillcient torender the catalyst bed inactive in a period of time representing only afraction of that required to produce objectionable packing of thecatalyst bed in the substantially complete absence of moisture.Accordingly, when treating such very sour stocks it is advantageous tointroduce a minor amount of nely dispersed aqueous NaOH or aqueousammonia directly to the stock entering the catalyzing zone and even toadd a minor amount of finely dispersed water at this point. Moisturethus supplied in limited quantities has the effect of washingaccumulated water soluble salts from the catalyst bed and thus deferringtermination of the sweetening operation occasioned by excessiveaccumulation of such salts in the catalyst bed. Any alkaline solution orwater introduced into the stock entering thecatalyzing zone must,however, be dispersed with extreme lneness in order to avoid theobjectionable elTects of wetting the catalyst bed. This may beaccomplished with particular advantage by injecting an NaOH solution asa fine stream which is immediately dispersed with extreme iineness, oratomized, by an impinging steam jet.

The effectiveness of my sweetening process is not appreciably aiected byvariations in temperature and pressure. Therefore, it may be carried outwith advantage at ordinary temperature and pressure although someimprovement has been noted with the use of elevated temperatures.alkaline distillate to the' catalyzing zone may be readily determined byvarying the charging rate under normal operating conditions. Thecharging rate is directly aiected by the amount of undesirable sulphurcompounds contained in the distillate. Increased size of the catalysttower greatly increases the maximum charging rate. I have found,however, that prolonged operation with a charging rate to the catalysttower substantially in excess of that which will permit propersweetening of the distillate will soon poison the catalyst. Theexistence of this condition is indicated during normal operation by arapid falling off of the maximum sweetening rate.

The conditions under which injection of' caustic soda and moisture intothe distillate entering the catalyzing zone are and are not desirable,and the effect of such injection, are Well illustrated by the followingcomparisons.

When treating a relatively sweet straight-run depropanized gasoline andmaintaining a high rate of flow through the catalyzing zone a number ofoperations embodying my process were carried out. In these operationsthe alkaline The maximum rate of charging compound was rst introducedinto andi admixed with the sour gasoline and the mixture then waspermitted to settle before passing to the catalyzing zone in order tominimize the presence of moisture in the catalyzing zone. In eachinstance the process vcontinued to sweeten the gasoline satisfactorilyuntil termination of the operation became necessary due to excessivepressure drop through the catalyst bed caused by packing. However, thiscondition was not reached until the average throughput per runsubstantially exceeded 59,000 barrels of gasoline. When operating inthis manner an increase in the moisture content of the mixture enteringthe catalyzing zone increased the tendency of the catalyst bed to pack,thus shortening the operation and the amount of distillate that could besweetened per run.

On the other hand when treating a very sour polymer gasoline by the sameprocedure as that employed in the operations above described butmaintaining that low rate of flow through the catalyzing zone which isessential to complete sweetening of the polymer gasoline, the activityof the catalyst bed became unsatisfactory for continued operation whenthe throughput reached a value of between 3,000 and 4,000 barrels ofpolymer gasoline. However, the pressure drop when this condition wasreached was not objectionably high. When treating the same type of verysour polymer gasoline, but using two catalyst towers in series andintroducing into the gasoline mixture entering the catalyzing towersNaOH in an amount slightly in excess of of theoretical and a smallamount of moisture supplied as steam to effect atomization of NaOH andmoisture, the process continued to operate satisfactorily until thethroughput exceeded 20,000 barrels of gasoline per tower.

One arrangement of apparatus adapted to carry out my novel sweeteningprocess is illustrated in the accompanying drawing in which Fig. 1 is adiagrammatic illustration of the relationship of the principal elementsand of the path of the distillate and reagents therethrough, while Fig.2 is a detailed view of one arrangement which has been foundparticularly useful for dispersing NaOH and moisture through the sourdistillate entering the catalyzing zone.

The process of my invention will be further described in connection withthe drawings. Referring to Fig. l a sour distillate, supplied throughline I, may be forced by pump 2 through line 3 into a settler 4. Acontrolled amount of alkaline compound, such, for example, as a solutionof caustic soda, or dry or aqueous ammonia, or a mixture of both, isintroduced into line 3 through line 5. The introduction of the mixtureof alkaline compound and sour distillate into settler 4 permitsseparation of the alkaline compound and entrained water from thedistillate, and any such material settling from the distillate mayadvantageously be returned through line 6 for reintroduction into line3. The alkaline distillate removed lfrom the top of settler 4 throughline 'I is thus substantially free from entrained moisture. Thisalkaline distillate enters line 8 and in part flows through backpressure valve 9 to line I0. At least a portion of the alkalinedistillate is fby-passed around valve 9 through sulphur control valve IIand thence through lines I2 and I3 into sulphur pot I4 containingelemental sulphur. Alkaline distillate containing dissolved sulphurleaves the top of sulphur pot I4 through line I5 and passes through lineIS to line IS where it` joins the distillate ilowing through backpressure valve 9.

Alternatively alkaline distillate by-passed through sulphur controlvalve H may be discharged through line l1 int-o the duplicate sulphurpot IB and discharged therefrom through line I9 to line I6; duplicatesulphur pots being provided to permit recharging of the pots withelemental sulphur without interruption of the sweetening process.

The alkaline distillate containing elemental sulphur which passesthrough line I then goes to the top of one of the catalyst towers 2D and2l. In the arrangement shown two catalyst towers are provided and thesecatalyst towers are tted with connections adapted to permit the alkalinesulphur-containing distillate to be passed downwardly through either ofthese towers separately, through both of them in multiple, or seriallyfirst through either one and then through the other. Each of thecatalyst towers 20 and 2| is provided near the bottom with a perforatedtray adapted to support the catalyst bed and with manheads arranged topermit removal of the catalytic material for reactivation. When it isdesired to operate the towers 2D and 2l in series, valves 22, 24, 25, 2Sand 21 are opened while valves 28, 29, 30 and 3i are closed. The sourgasoline then iiows from line IU through lines 32 and 33 into the upperend of the tower 20 and from the lower end of tower 2U through lines 35,31, 38 and 39 to the upper end of tower 2i. From the lower end of tower2l the sweetened distillate is discharged through lines 4!, 42 and 43.Pressure gauges 50, l and 52 advantageously are provided to permitobservation of the pressure drops through the towers 2U and 2|.

In passing from line 33 to the upper end of tower the sour distillatepasses through a T 34 which is illustrated in greater detail in Fig. 2.Through a flange on the one end of this T 34, there extends a steam line45 and an alkali line 46.

As illustrative of one arrangement which has been found to giveparticularly satisfactory rcsults in an apparatus in which line 33 and T34 comprise a 4 inch line and 4 inch T, respectively, the steam line 45may consist of a 1/4 inch pipe which has been drawn closed at thedischarge end and then drilled axially to provide a discharge aperturele in diameter. The alkali line 46 may similarly comprise a 1A; inchpipe to the discharge end of which is attached a 1/8 inch steel tubeupwardly curved and terminating in a horizontal plane extending alongthe axis of the discharge aperture of steam line 45. A brace 49 isprovided to maintain the discharge ends of conduits 45 and 46 in fixedrelationship. This arrangement has been found especially adapted forintroducing NaOH and moisture in limited amounts and in a very. finelyand uniformly dispersed state into the distillate flowing through line33 and T 34. A limited amount of moisture, as steam, and NaOH areadvantageously supplied in this manner particularly when treating verysour distillates, which require low throughput rates thus increasing themoisture tolerance. In fact when treating very sour distillates suchthat the moisture tolerance of the process is sufficiently high all ofthe alkalinity may be supplied in this manner. Under these conditionsthe sour distillate from line i may be lay-passed to line 8 through line53 and the functions of line 5 and settler l dispensed with entirely.

A T 40 with a steam line 41 and alkali line 4S, similar in constructionto T 34 and its associated steam and alkali lines 45 and 45, may bedisposed in line 39 adjacent the inlet of tower 2l. The steam and alkalilines 41 and 48 permit injection of finely dispersed moisture and alkaliinto the distillate entering tower 2l when tower 2l is -being operatedindependently or in parallel with tower 2D. When treating a moderatelysour stock additional alkali need not be introduced at this point iftowers 20 and 2l are being operated in series in the manner abovedescribed. However in the case of extremely sour distillates a part ofthe required total amount of alkali is injected at this point as it isdesired to reduce the alkalinity in tower 20 and yet maintain thedistillate in an alkaline condition throughout the period of catalystcontact.

It will be apparent that, although only two catalyst towers have beenillustrated, additional catalyst towers may be used if desired and suchadditional catalyst towers may be operated in multiple with, or inseries with, catalyst towers 2U and 2|. Usually the progressivelyincreasing pressure drop occasioned by the tendency of the catalyst bedto pack renders the use of more than two towers in series undesirable.When two towers have been operated in series until the distillate is nolonger sweetened and it is found that the pressure drop has not as yetbe come objectionably high, a tower including a freshly reactivatedcharge of catalyst may be inserted in the #2 position and the sweeteningoperation continued using the partially spent catalyst previouslyemployed in the #2 position in the #l position.

The following specio examples will serve to further illustrate myinvention as applied to various types of gasoline. Three groups of fiveruns each were carried out in apparatus of the type illustrated in thedrawings using a single catalyst tower and under operating conditionswhich involved introduction of all of the alkaline compound through line5. The first group of runs was applied to a moderately sour lightgasoline flashed from crude oil of 340 F. and 4) pounds pressure and wassubsequently depropanized in a tower where it was stripped under 200pounds pressure while maintaining a temperature of 3l03l5 F. in thedepropanizer reboiler thereby producing a gasoline having a Reid vaporpressure of about 14l5 pounds. The second group of runs was applied to amoderately sour heavy gasoline which was obtained from a crude oil stilland lye-washed before being charged to my sweetening operation. Thethird group of operations was applied to a sour reformed gasoline whichwas obtained from a reforming still and then debutanized. Thedebutanized reformed gasoline was then passed directly to my sweeteningprocess. The catalyst tower employed in all of the above-describedoperations had a capacity of about 9 cu. ft. The catalyst in each runconsisted of a saw-dustlead sulphide mixture prepared as described aboveand containing about 30%-60% lead sulphide in its active condition.Acetone was used above described for washing the catalyst duringreactivation of the catalyst between runs and the presence of air intothe treating operations was avoided so far as possible. The results ofYeach of the three groups of runs above mentioned -catalyst contained:S-60% lead sulphide in its are given below in tabular form:

Light Heavy Reformed Gasoline gasoline gasoline gasoline Total bbls.gasoline treated 238, 507 298, 816 75, 121 Total cubic foot catal 47.34. 91 23. 81 Total hours on stream 2, 486 3, 098 1, 505 Total sulphurused, pounds. 71 1, 307 512 Average length of run, hours 497 619 301Average bbls. gasoline per cu. ft.

of catalyst 5, 030 8, 560 3, 155 Average bbls. gasoline per run 47, 70069, 763 15, 024 Average cu. it. catalyst per rxm 9. 5 6. 98 4. 72 Lbs.sulphur per 1,000 bbls 3.0 4. 37 6. 80 Lbs. NaOH per 1,000 bbls 12.15 6.57 20. 25 Lbs. NH3 per 1,000 bbls 1. 35 0.164 Total acetone wash perrun; 700 700 350 The treated gasolines were completely sweetened, asshown by the standard doctor test, andwere non-corrosive as indicated bythe copper-strip test.

The following additional specic example illustrates an application ofmyv process in the sweetening of very sour polymer gasoline. A polymergasoline having a mercaptan content of 0.025% was supplied through pipel and bypassed through line 53 to line 8. A portion of this gasoline wasdiverted through one of the sulphur pots at a rate controlled toincorporate the predetermined quantity of elemental sulphur in themixture passing through line I0. This mixture was passed seriallythrough catalyst towers 20 and 2l each of which was charged with acatalyst bed containing 62 cu. ft. of the saw dust-lead sulphidecatalyst previously described. All of the alkaline compound used in thisoperation was introduced into the polymer gasoline entering thecatalyzing towers, a portion being introduced into T 34 adjacent theinlet of the rst catalyzing tower and the remainder into T 40 adjacentthe inlet of the second catalyzing tower. This was supplied throughlines 46 and d8 as an aqueous NaOH solution of about 25 B. This NaOH wasnely dispersed through the sour polymer gasoline by steam suppliedthrough lines l5 and 41. Operating in this manner the process continuedto satisfactorily sweeten the polymer gasoline for 300 hours duringwhich time 12000 bbls. of gasoline were passed through the apparatus.Upon substitution of a :freshly reactivated catalyst bed in the secondposition and transfer of the partially spent catalyst bed from thesecond to rst position the operation was resumed and continued tosweeten the polymer gasoline satisfactorily until an additional 12,0001bbls. had been passed through the system. During this period sulphur wasused at an average rate of 30 pounds per thousand barrels of gasoline.The NaOH solution was supplied at an average rate sufceint to provide 70pounds of NaOH per thousand barrels of gasoline. Steam was supplied atan average rate of 600 pounds per thousand barrels of gasoline.

If desired the preliminary alkaline treatment may be eliminated evenwhen treating moderately sour distillates. The following specificexample is illustrative of such an operation. In this operation thestock treated was a kerosene distillate derived from a mixture of EastTexas and Midcontinent crudes. Only one catalyst tower was employed, thecatalyst bed having a capacity of 120 cubic feet. The catalyst used wasa saw dust-lead sulphide mixture which had previously been used in theprocess of my invention and had been regenerated without acetone washingin the manner above described. This active condition. All of thealkalinity was obtained by dispersing, with steam, aqueous caustic ksodaand ammonium hydroxide into the stream of sour distillate entering thecatalyst tower. The results obtained in this operation are given in thefollowing table:

Total bbls. gasoline treated 274,274 Total cubic foot catalyst Totalhours on stream 1998 Total sulphur used, lbs 898 Average bbls. keroseneper cu. ft.

catalyst 2280 Lbs. sulphur per 1000 bbls 43.28 Lbs. NaOH per 1000 bbls..2&1 Lbs. NHiOl-I per 1000 bbls .77

Lbs. water as steam per 1000 bbls.. 5

distillates by the process of my invention is only a small fraction ofthe cost of treating such distillates by the conventional doctortreatment. The high emulsion and washing losses concomitant withconventional doctor treatment are eliminated and the required operatinglabor is materially reduced. My process also eliminates the necessity ofhandling large volumes of aqueous solution which are particularlydifficult to handle during coldweather as found by common experience inheretofore conventional practice. In addition my process may be appliedto gasolines without impairing their anti-knock properties.

I claim:

1. The method of removing undesirable sulphur compounds from a lightpetroleum distillate which comprises incorporating in thedistillate anamount of elemental sulphur substantially equal to the lamount ofelemental sulphur required to combine with said sulphur compounds landan amount o-f an alkaline compound suffithan a smal-1 amount of addediinely dispersed water.

2. The method of removing undesirable sulphur compounds from a lightpetroleum distillate which comprises incorporating in the distillate anamount of elemental sulphur substantially equal to the amount ofelemental sulphur required to combine with said sulphur compounds andanamount of an alkaline compound sui'licient to render and maintain thedistillate alkaline, and passing the alkaline distillate containingelemental sulphur in intimate contact with a catalyst comprising asulphide of a polyvalent metal in the absence of any substantial amountof free oxygen and undispersed water and in the presence of not morethan a small amount of added finely dispersed water.

3. 'Ihe method of removing undesirable sulphur compounds from a lightpetroleum distillate containing a substantial quantity of such sulphurcompounds which consists of incorporating in the distillate an amount ofelemental sulphur substantially equal to the amount of sulphur requiredto combine With said sulphur compounds and an amount of an alkalihydroxide sufficient to render and maintain the distillate alkaline, andpassing the alkaline distillate containing elemental sulphur in intimatecontact with a lead sulphide catalyst in the absence oi any substantialamount of free oxygen and undispersed Water and in the presence of asmall amount of added finely dispersed Water.

4. The method of removing undesirable sulphur compounds from a lightpetroleum distillate which comprises incorporating in the distillate anamount of elemental sulphur substantially equal to the amount of sulphurrequired to combine with said sulphur compounds, passing the alkalinedistillate containing elemental sulphur in intimate contact with a leadsulphide catalyst in a plurality of successive stages, said catalystcontact being effected in the absence of any substantial amount of freeoxygen and undispersed Water and in the presence of not more than asmall amount of finely dispersed water, and incorporating in thedistillate prior to each stage of contact with said catalyst an amountof an alkali hydroxide suhcient to maintain the distillate alkalineduring the immediately following stages of catalyst contact.

5. The method of removing undesirable sulphur compounds from a lightpetroleum distillate which comprises incorporating in the distillate anamount of elemental sulphur substantially equal to the amount of sulphurrequired to coinbine With said sulphur compounds and an amount ofalkaline compounds suflicient to render and maintain the distillatealkaline, and passing the alkaline distillate containing elementalsulphur in intimate contact with lead sulphide deposited on saw-dust,said contact being eiected in the absence of any substantial amount offree oxygen and undispersed Water and in the presence of not more than asmall amount of added finely dispersed Water.

6. The method of removing undesirable sulphur compounds from a lightpetroleum distillate containing a substantial quantity of such compoundsWhich comprises incorporating in said distillate an amount of elementalsulphur substantially equal to the amount of sulphur required to combinewith said sulphur compounds, passing the resulting mixture in intimatecontact with a lead sulphide catalyst in a catalyzing zone,

finely dispersing through the sulphur containing distillate as it entersthe catalyzing zone a small amount of Water and an amount of an alkalihydroxide slightly in excess of that required to maintain saiddistillate in an alkaline condition throughout its contact with saidcatalyst, and

maintaining the catalyzing zone free from undispersed Water and 'anysubstantial amount of free oxygen.

7. In the treatment of a light petroleum distillate containing asubstantial quantity of un desirable sulphur compounds for the removalof said sulphur compounds therefrom wherein a small amount of elementalsulphur and an amount of alkali hydroxide suiiicient to render thedistillate alkaline are incorporated in said distillate and the mixturethen passed in contact with a lead sulphide catalyst in a catalyzingzone in the absence of any substantial amount of free oxygen andundispersed water, the improvement which comprises nely dispersing aminor amount of water through the distillate as it enters the catalyzingzone by injecting steam into said distillate.

8. In the treatment of a light petroleum distillate containing asubstantial quantity of undesirable sulphur compounds for the removal ofsaid sulphur compounds therefrom wherein a small amount of elementalsulphur and an amount of alkali hydroxide sui`n`cient to render thedistillate alkaline are incorporated in said distillate and the mixturethen passed in contact with a lead sulphide catalyst in a catalyzingzone in the absence of any substantial amount of free oxygen andundispersed water, the improvement which comprises nely dispersing saidalkali hydroxide and a minor amount of Water through said distillate asit enters the catalyzing zone by introducing thereinto steam and saidalkali hydroxide as impinging streams.

9. In the treatment of a light distillate containing a substantialamount of undesirable sulphur compounds for the removal of said sulphurcompounds therefrom, the improvement which comprises incorporating asmall amount of elemental sulphur in said distillate and passing themixture in contact with lead sulphide deposited on saw-dust in acatalyzing zone, and finely dispersing through the distillate as itenters said catalyzing zone an amount of alkali hydroxide suiiicient torender the distillate alkaline and a small amount of steam.

10. The method of removing undesirable sulphur compounds from a lightpetroleum distillate which consists of incorporating in the distillatean amount of elemental sulphur substantially equal to the amount ofsulphur required to combine With said sulphur compounds and sodiumhydroxide in an amount sufficient to render the distillate alkaline,passing the alkaline distillate containing elemental sulphur in Contactwith a catalyst comprising a sulphide of a polyvalent metal, in thepresence of not more than a small amount of finely dispersed water, andexcluding from the catalyzing Zone any substantial amount of free oxygenand undispersed water.

RICHARD O. BENDER.

